Comunidades zooplanctônicas como bioindicadoras da qualidade da água de quatro reservatórios da região semi-árida do Rio Grande do Norte

The response of zooplankton assemblages to variations in the water quality of four man-made lakes, caused by eutrophication and siltation, was investigated by means of canonical correspondence analysis. Monte Carlo simulations using the CCA eingenvalues as test statistics revealed that changes in zooplankton species composition along the environmental gradients of trophic state and abiogenic turbidity were highly significant. The species Brachionus calyciflorus, Thermocyclops sp. and Argyrodiaptomus sp. were good indicators of eutrophic conditions while the species Brachionus dolabratus, Keratella tropica and Hexarthra sp. were good indicators of high turbidity due to suspended sediments. The rotifer genus Brachionus was the most species-rich taxon, comprising five species which were associated with different environmental conditions. Therefore, we tested whether this genus alone could potentially be a better biological indicator of these environmental gradients than the entire zooplankton assemblages or any other random set of five species. The ordination results show that the five Brachionus species alone did not explain better the observed pattern of environmental variation than most random sets of five species. Therefore, this genus could not be selected as a target taxon for more intensive environmental monitoring as has been previously suggested by Attayde and Bozelli (1998). Overall, our results show that changes in the water quality of man-made lakes in a tropical semi-arid region have significant effects on the structure of zooplankton assemblages that can potentially affect the functioning of these ecosystems

Multiscale evaluation of thermal dependence in the glucocorticoid response of vertebrates

Environmental temperature has profound effects on animal physiology, ecology, and evolution. Glucocorticoid (GC) hormones, through effects on phenotypic performance and life history, provide fundamental vertebrate physiological adaptations to environmental variation, yet we lack a comprehensive understanding of how temperature influences GC regulation in vertebrates. Using field studies and metaand comparative phylogenetic analyses, we investigated how acute change and broadscale variation in temperature correlated with baseline and stress-induced GC levels. Glucocorticoid levels were found to be temperature and taxon dependent, but generally, vertebrates exhibited strong positive correlations with acute changes in temperature. Furthermore, reptile baseline, bird baseline, and capture stressinduced GC levels to some extent covaried with broadscale environmental temperature. Thus, vertebrate GC function appears clearly thermally influenced. However, we caution that lack of detailed knowledge of thermal plasticity, heritability, and the basis for strong phylogenetic signal in GC responses limits our current understanding of the role of GC hormones in species’ responses to current and future climate variation.

Hierarchical spatial segregation of two Mediterranean vole species: the role of patch‑network structure and matrix composition

According to ecological theory, the coexistence of competitors in patchy environments may be facilitated by hierarchical spatial segregation along axes of environmental variation, but empirical evidence is limited. Cabrera and water voles show a metapopulation-like structure in Mediterranean farmland, where they are known to segregate along space, habitat, and time axes within habitat patches. Here, we assess whether segregation also occurs among and within landscapes, and how this is influenced by patch-network and matrix composition. We surveyed 75 landscapes, each covering 78 ha, where we mapped all habitat patches potentially suitable for Cabrera and water voles, and the area effectively occupied by each species (extent of occupancy). The relatively large water vole tended to be the sole occupant of landscapes with high habitat amount but relatively low patch density (i.e., with a few large patches), and with a predominantly agricultural matrix, whereas landscapes with high patch density (i.e.,many small patches) and low agricultural cover, tended to be occupied exclusively by the small Cabrera vole. The two species tended to co-occur in landscapes with intermediate patch-network and matrix characteristics, though their extents of occurrence were negatively correlated after controlling for environmental effects. In combination with our previous studies on the Cabrera-water vole system, these findings illustrated empirically the occurrence of hierarchical spatial segregation, ranging from withinpatches to among-landscapes. Overall, our study suggests that recognizing the hierarchical nature of spatial segregation patterns and their major environmental drivers should enhance our understanding of species coexistence in patchy environments.

P2-486 Environmental temperature variation and morbidity: a meta-analysis

Extreme temperatures have been shown to have a detrimental effect on health. Hot temperatures can increase the risk of mortality, particularly in people suffering from cardiorespiratory diseases. Given the onset of climate change, it is critical that the impact of temperature on health is understood, so that effective public health strategies can correctly identify vulnerable groups within the population. However, while effects on mortality have been extensively studied, temperature–related morbidity has received less attention. This study applied a systematic review and meta–analysis to examine the current literature relating to hot temperatures and morbidity.

Analysis of environmental efficiency variation : a materials balance approach

Recent literature has argued that environmental efficiency (EE), which is built on the materials balance (MB) principle, is more suitable than other EE measures in situations where the law of mass conversation regulates production processes. In addition, the MB-based EE method is particularly useful in analysing possible trade-offs between cost and environmental performance. Identifying determinants of MB-based EE can provide useful information to decision makers but there are very few empirical investigations into this issue. This article proposes the use of data envelopment analysis and stochastic frontier analysis techniques to analyse variation in MB-based EE. Specifically, the article develops a stochastic nutrient frontier and nutrient inefficiency model to analyse determinants of MB-based EE. The empirical study applies both techniques to investigate MB-based EE of 96 rice farms in South Korea. The size of land, fertiliser consumption intensity, cost allocative efficiency, and the share of owned land out of total land are found to be correlated with MB-based EE. The results confirm the presence of a trade-off between MB-based EE and cost allocative efficiency and this finding, favouring policy interventions to help farms simultaneously achieve cost efficiency and MP-based EE.

Understanding past climate variation and environmental change for the future of an iconic landscape – K'gari Fraser Island, Queensland, Australia

The unique combination of landscapes and processes that are present and operate on Fraser Island (K'gari) create a dynamic setting that is capable of recording past environmental events, climate variations and former landscapes. Likewise, its geographic position makes Fraser Island sensitive to those events and processes. Based on optically stimulated luminescence dating, the records archived within the world's largest sand island span a period that has the potential to exceed 750 ka and contain specific records that are of extremely high resolution over the past 40,000 years. This is due to the geographic position of Fraser Island, which lies in the coastal subtropical region of Queensland Australia. Fraser Island is exposed to the open ocean currents of the Coral Sea on the east coast and the waters of Hervey Bay on its western margin and is positioned to receive moisture from the Indo-Australian monsoon, southeast trade winds and experiences occasional tropical and ex-tropical cyclones. We review literature that presents the current level of understanding of sea level change, ecological variation and environmental change on Fraser Island. The previous works illustrate the importance of Fraser Island and may link processes, environments and climates on Fraser Island with global records.

Short-term variation of CO2 flux in relation to environmental controls in an alpine meadow on the Qinghai-Tibetan Plateau

[1] The alpine meadow ecosystem on the Qinghai-Tibetan Plateau may play a significant role in the regional carbon cycle. To assess the CO2 flux and its relationship to environmental controls in the ecosystem, eddy covariance of CO2, H2O, and energy fluxes was measured with an open-path system in an alpine meadow on the plateau at an elevation of 3,250 m. Net ecosystem CO2 influx (Fc) averaged 8.8 g m(-2) day(-1) during the period from August 9 to 31, 2001, with a maximum of 15.9 g m(-2) day(-1) and a minimum of 2.3 g m(-2) day(-1). Daytime Fc averaged 16.7 g m(-2) day(-1) and ranged from 10.4 g m(-2) day(-1) to 21.7 g m(-2) day(-1) during the study period. For the same photosynthetic photon flux density (PPFD), gross CO2 uptake (Gc) was significantly higher on cloudy days than on clear days. However, mean daily Gc was higher on clear days than on cloudy days. With high PPFD, Fc decreased as air temperature increased from 10degreesC to 23degreesC. The greater the difference between daytime and nighttime air temperatures, the more the sink was strengthened. Daytime average water use efficiency of the ecosystem (WUEe) was 8.7 mg (CO2)(g H2O)(-1); WUEe values ranged from 5.8 to 15.3 mg (CO2)(g H2O)(-1). WUEe increased with the decrease in vapor pressure deficit. Daily albedo averaged 0.20, ranging from 0.19 to 0.22 during the study period, and was negatively correlated with daily Fc. Our measurements provided some of the first evidence on CO2 exchange for a temperate alpine meadow ecosystem on the Qinghai-Tibetan Plateau, which is necessary for assessing the carbon budget and carbon cycle processes for temperate grassland ecosystems.

Living to the range limit: consumer isotopic variation increases with environmental stress

Background: Theoretically, each species’ ecological niche is phylogenetically-determined and expressed spatially as the species’ range. However, environmental stress gradients may directly or indirectly decrease individual performance, such that the precise process delimiting a species range may not be revealed simply by studying abundance patterns. In the intertidal habitat the vertical ranges of marine species may be constrained by their abilities to tolerate thermal and desiccation stress, which may act directly or indirectly, the latter by limiting the availability of preferred trophic resources. Therefore, we expected individuals at greater shore heights to show greater variation in diet alongside lower indices of physiological condition.

Methods: We sampled the grazing gastropod Echinolittorina peruviana from the desert coastline of northern Chile at three shore heights, across eighteen regionally-representative shores. Stable isotope values (δ13C and δ15N) were extracted from E. peruviana and its putative food resources to estimate Bayesian ellipse area, carbon and nitrogen ranges and diet. Individual physiological condition was tracked by muscle % C and % N.

Results: There was an increase in isotopic variation at high shore levels, where E. peruviana’s preferred resource, tide-deposited particulate organic matter (POM), appeared to decrease in dietary contribution, and was expected to be less abundant. Both muscle % C and % N of individuals decreased with height on the shore.

Discussion: Individuals at higher stress levels appear to be less discriminating in diet, likely because of abiotic forcing, which decreases both consumer mobility and the availability of a preferred resource. Abiotic stress might be expected to increase trophic variation in other selective dietary generalist species. Where this coincides with a lower physiological condition, this may be a direct factor in setting their range limit.

Genetic variation of and environmental effects on inducibility of resistance in tomatoes (Solanum lycopersicum L.) to Phytophthora infestans (Mont) de Bary

Many plant strengtheners are promoted for their supposed effects on nutrient uptake and/or resistance induction (IR). In addition, many organic fertilizers are supposed to enhance plant health and several studies have shown that tomatoes grown organically are more resistant to late blight, caused by Phytophthora infestans to tomatoes grown conventionally. Much is known about the mechanisms underlying IR. In contrast, there is no systematic knowledge about genetic variation for IR. Therefore, the following questions were addressed in the presented dissertation: (i) Is there genetic variation among tomato genotypes for inducibility of resistance to P. infestans? (ii) How do different PS compare with the chemical inducer BABA in their ability to IR? (iii) Does IR interact with the inducer used and different organic fertilizers? A varietal screening showed that contrary to the commonly held belief IR in tomatoes is genotype and isolate specific. These results indicate that it should be possible to select for inducibility of resistance in tomato breeding. However, isolate specificity also suggests that there could be pathogen adaptation. The three tested PS as well as two of the three tested organic fertilisers all induced resistance in the tomatoes. Depending on PS or BABA variety and isolate effects varied. In contrast, there were no variety and isolate specific effects of the fertilisers and no interactions with the PS and fertilisers. This suggests that the different PS should work independent of the soil substrate used. In contrast the results were markedly different when isolate mixtures were used for challenge inoculations. Plants were generally less susceptible to isolate mixtures than to single isolates. In addition, the effectiveness of the PS was greater and more similar to BABA when isolate mixtures were used. The fact that the different PS and BABA differed in their ability to induce resistance in different host genotype -pathogen isolate combinations puts the usefulness of IR as a breeding goal in question. This would result in varieties depending on specific inducers. The results with the isolate mixtures are highly relevant. On the one hand they increase the effectiveness of the resistance inducers. On the other hand, measures that increase the pathogen diversity such as the use of diversified host populations will also increase the overall resistance of the hosts. For organic tomato production the results indicate that it is possible to enhance the tomato growing system with respect to plant health management by using optimal fertilisers, plant strengtheners and any measures that increase system diversity.

Genetic and environmental influences on variation in balance performance among female twin pairs aged 21-82 years

Genetic and environmental influences on variation in balance performance were measured in 93 monozygous and 83 dizygous female twin pairs aged 21–82 years (mean age, 50.5 years) in Melbourne, Australia, between 1999 and 2003. The authors administered clinical (Lord's Balance Test and Step Test) and laboratory tests of static and dynamic balance from the Chattecx Balance System with and without distractor tasks. The authors conducted factor analysis and estimated genetic and environmental variance components and heritability (defined as additive genetic variance as a proportion of all variance, after adjustment for age) using a multivariate normal model with the statistical package FISHER. Three factors were identified and adjusted for age. Heritability was 46% (standard error (SE), 9) for the "sensory balance tests" factor and 30% (SE, 9) for the "static and dynamic perturbations" factor. For both factors, the remaining variance was attributed to unique environmental effects. There was no evidence that genetic factors influenced variation in the "dynamic weight shift tests" factor, with environmental effects shared by twins accounting for 38% (SE, 7) of variance. Neither genetic nor environmental proportions of variance differed significantly between twin subgroups by age (≤50/>50 years). An age-related decline in performance measures was found across the whole sample. These results imply that balance impairments may have a heritable element.

Spatial-temporal variation of Paralonchurus brasiliensis (Actinopterygii: Sciaenidae) density in relation to some environmental factors on the inner shelf of south-eastern Brazilian coast

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)